It is well-known to grow plants (including seedlings) in portable seed trays, pots and the like. These plants must receive a periodic supply of liquid necessary for growth and sustenance. In a wide range of applications extending from commercial nurseries through domestic greenhouses to indoor pot plants it is convenient to supply the plants with liquid on an automatic basis.
Automatic irrigation systems suitable for plants in seed trays, pots and the like have been developed but these systems have disadvantages. Three disadvantages are commonly found. One is that the system requires a pump, which adds to the expense of the system and complicates its installation and use. Secondly, the period of watering and hence the amount of liquid supplied cannot easily be controlled. Further, a spray is often used, making the system impractical for use in the home. U.S. Pat. No. 4,211,037 and German Offenlegungsschrift No. 2537135 both disclose an automatic watering system which requires a pump to give the head necessary to supply the liquid. Although both systems provide a drain, and a timer can be used in conjunction with the pump to control the liquid supply, the necessity for a pump introduces undesirable expense and complexity. On the other hand U.S. Pat. No. 3,906,667 and German Offenlegungsschrift No. 2854198 disclose systems of dispensing liquids to plants which do not require the use of a pump but these systems result in a continuous supply of liquid unless the supply is exhausted or unless there is human intervention.
It is an object of the present invention to provide an apparatus for dispensing the required liquids to plants in plant containers which overcomes or mitigates these disadvantages.